1. Field of the Invention
The present invention relates to a laser printer carrying out a printing process on a continuous form which is perforated at appropriate intervals to enable the continuous form to be separated into single pages. More particularly, it relates to a device for controlling a process of stopping the laser printer.
2. Description of the Related Art
The continuous form referred to in this specification is a fan-folded paper form which is foldable and is provided with sprocket holes, and is constructed in such a manner that the folding portions thereof correspond to perforations by which the continuous form is easily separated into individual pages. Usually, the continuous form is printed with ruled lines extending in a direction perpendicular to a feeding direction, at predetermined intervals, and a predetermined positional relationship exists between the sprocket holes and ruled lines.
Generally, a laser printer carrying out the printing of an image on the continuous form is provided with a printing unit having a sensitive drum on which an electrostatic latent image is formed, a developing unit for developing the electrostatic latent image using a toner, and a transfer unit for transferring the developed toner image to the continuous form. In such as laser printer, the continuous form to which the image is transferred by the printing unit is fed to fixing rollers by a feeding unit, the image is fixed to the continuous form by the fixing rollers, and the continuous form is then discharged from the laser printer.
Further, such a laser printer is provided with a plurality of error sensors for sensing various errors, such as a jam of the continuous form, a shortage of toner, and an overflow of discharged toner, and an emergency stop of the operation of the printing unit, the feeding unit and the fixing rollers is made when an error is detected by the error sensors.
In the laser printer, the errors are divided into two categories; i.e., a high priority error, such as a paper jam, which requires an emergency stop of the printing process, and a low priority error such as a shortage of toner and an overflow of discharged toner, which does not require an emergency stop of the printing process. Nevertheless, in both cases, an emergency stop of the operation of the printing unit, the feeding unit and the fixing rollers is carried out, and therefore, if a low priority error occurs when only half of a page has been printed, the printing unit, the feeding unit and the fixing rollers are stopped, and thus printing of that page is ended at a point midway down the page. Accordingly, when the error is corrected and the printing process is restarted, if the page on which the printing is ended midway down the page is discharged from the printer, and a the next page is printed again from the beginning, a problem arises in that the page on which the printing is ended midway down the page is wasted.